U.S. patent number 11,196,035 [Application Number 16/276,922] was granted by the patent office on 2021-12-07 for anode of lithium battery, method for fabricating the same, and lithium battery using the same.
This patent grant is currently assigned to HON HAI PRECISION INDUSTRY CO., LTD., Tsinghua University. The grantee listed for this patent is HON HAI PRECISION INDUSTRY CO., LTD., Tsinghua University. Invention is credited to Lu Chen, Ze-Cheng Hou, Wen-Zhen Li, Yuan-Feng Liu, Lin Zhu.
United States Patent |
11,196,035 |
Liu , et al. |
December 7, 2021 |
Anode of lithium battery, method for fabricating the same, and
lithium battery using the same
Abstract
An anode of the lithium ion battery is provided. The anode of
the lithium ion battery comprises a nanoporous copper substrate and
a copper oxide nanosheet array. The copper oxide nanosheet array is
disposed on one surface of the nanoporous copper substrate, and the
nanoporous copper substrate is chemically bonded to the copper
oxide nanosheet array.
Inventors: |
Liu; Yuan-Feng (Beijing,
CN), Hou; Ze-Cheng (Beijing, CN), Chen;
Lu (Beijing, CN), Zhu; Lin (Beijing,
CN), Li; Wen-Zhen (Beijing, CN) |
Applicant: |
Name |
City |
State |
Country |
Type |
Tsinghua University
HON HAI PRECISION INDUSTRY CO., LTD. |
Beijing
New Taipei |
N/A
N/A |
CN
TW |
|
|
Assignee: |
Tsinghua University (Beijing,
CN)
HON HAI PRECISION INDUSTRY CO., LTD. (New Taipei,
TW)
|
Family
ID: |
69946653 |
Appl.
No.: |
16/276,922 |
Filed: |
February 15, 2019 |
Prior Publication Data
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|
|
|
Document
Identifier |
Publication Date |
|
US 20200106085 A1 |
Apr 2, 2020 |
|
Foreign Application Priority Data
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|
|
|
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Sep 29, 2018 [CN] |
|
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201811146948.2 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H01M
4/1391 (20130101); H01M 4/485 (20130101); H01M
4/80 (20130101); H01M 10/052 (20130101); H01M
4/665 (20130101); H01M 4/661 (20130101); H01M
4/0492 (20130101); H01M 10/0525 (20130101); H01M
4/131 (20130101); H01M 2004/027 (20130101); H01M
2004/021 (20130101); Y02E 60/10 (20130101) |
Current International
Class: |
H01M
4/131 (20100101); H01M 4/485 (20100101); H01M
4/1391 (20100101); H01M 10/0525 (20100101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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102013470 |
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Apr 2011 |
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CN |
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102690968 |
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Sep 2012 |
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CN |
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103578784 |
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Feb 2014 |
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CN |
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105762327 |
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Jul 2016 |
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CN |
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106229462 |
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Dec 2016 |
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CN |
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106229462 |
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Dec 2016 |
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CN |
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106410227 |
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Feb 2017 |
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CN |
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106947995 |
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Jul 2017 |
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CN |
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108597892 |
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Sep 2018 |
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CN |
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201106524 |
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Feb 2011 |
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TW |
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Other References
Qi, Z., Zhao, C., Wang, X., Lin, J., Shao, W., Zhang, Z., &
Bian, X. (2009). Formation and Characterization of Monolithic
Nanoporous Copper by Chemical Dealloying of Al--Cu Alloys. The
Journal of Physical Chemistry C(113), 6694-6698. (Year: 2009).
cited by examiner .
Aburada, et al. (2011). Synthesis of nanoporous copper by
dealloying of Al--Cu--Mg amorphous alloys in acidic solution: The
effect of nickel. Corrosion Science(53), 1627-1632. (Year: 2011).
cited by examiner .
Facile fabrication of CuO mesoporous nanosheet cluster array
electrodes with super lithium-storage properties, Xin Chen, et al.,
Journal of Materials Chemistry, vol. 22, No. 27, pp. 13637-13642.
cited by applicant.
|
Primary Examiner: Cano; Milton I
Assistant Examiner: Shulman; Jenna
Attorney, Agent or Firm: ScienBiziP, P.C.
Claims
What is claimed is:
1. A method for making an anode of the lithium ion battery,
comprising: dealloying a copper alloy substrate to form a
nanoporous copper substrate, wherein the nanoporous copper
substrate consists of a nanoporous copper; placing the nanoporous
copper substrate in an alkaline solution comprising an ammonium ion
thereby the nanoporous copper substrate floats on a surface of the
alkaline solution comprising the ammonium ion; setting up
conditions wherein the nanoporous copper substrate react with the
alkaline solution comprising the ammonium ion to form a composite
material; and drying the composite material to form a nanoporous
copper supported copper oxide nanosheet array composite, wherein
the copper oxide nanosheet array comprises a plurality of copper
oxide nanosheets, and the plurality of copper oxide nanosheets are
perpendicularly with the nanoporous copper substrate.
2. The method as claimed in claim 1, wherein the alkaline solution
comprising the ammonium ion is an ammonium solution or a sodium
hydroxide solution.
3. The method as claimed in claim 1, wherein a concentration of the
alkaline solution comprising the ammonium ion is ranged from about
0.016 mol/L to about 1 mol/L.
4. The method as claimed claim 1, the method of setting up
conditions comprising contacting a surface of the nanoporous copper
substrate with the alkaline solution comprising the ammonium
ion.
5. The method as claimed claim 1, the method of setting up
conditions comprising allowing the nanoporous copper substrate to
oxidize for 1 hour to 72 hours.
6. The method as claimed claim 1, the method of drying the
composite material comprising setting a drying temperature and a
drying time period of the composite material.
7. The method as claimed claim 1, further comprising washing the
nanoporous copper substrate is washed to remove an oxide layer on a
surface of the nanoporous copper substrate before placing the
nanoporous copper substrate in the alkaline solution.
8. The method as claimed claim 1, wherein the nanoporous copper is
oxidized to form a copper hydroxide array during the process of the
nanoporous copper substrate reacting with the alkaline
solution.
9. The method as claimed claim 8, wherein a surface of the
nanoporous copper substrate in contact with the alkaline solution
comprising the ammonium ion is oxidized, and a surface of the
nanoporous copper substrate exposed to air is not oxidized.
10. The method as claimed claim 1, wherein the nanoporous copper
substrate comprises a reinforcement, and the reinforcement is a
carbon nanotube structure or a graphene.
11. The method as claimed claim 1, wherein a material of the copper
alloy substrate is a copper-zinc alloy or a copper-aluminum
alloy.
12. The method as claimed claim 1, wherein a thickness of the
nanoporous copper substrate ranges from about 0.01 mm to about 1
mm.
13. The method as claimed claim 1, wherein the nanoporous copper
substrate has a plurality of pores, and a diameter of each of the
pores ranges from about 20 nm to about 200 nm.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
This application claims all benefits accruing under 35 U.S.C.
.sctn. 119 from China Patent Application No. 201811146948.2, filed
on Sep. 29, 2018, in the China National Intellectual Property
Administration, the contents of which are hereby incorporated by
reference. The application is also related to copending application
entitled, "NANOPOROUS COPPER SUPPORTED COPPER OXIDE NANOSHEET ARRAY
COMPOSITES AND METHOD THEREOF", filed Feb. 15, 2019 (Ser. No.
16/276,919).
FIELD
The present disclosure relates to an anode of lithium battery,
method for fabricating the anode, and lithium battery using the
anode.
BACKGROUND
A lithium ion battery has become an ideal power source of portable
electronic devices and environmentally-friendly electric vehicles
due to their high mass and volumetric capacity, high output
voltage, low self-discharge rate, wide operating temperature range,
fast charge and discharge, and no memory effect. With the
popularization of portable electronic devices and the development
of electric vehicles, the lithium ion battery will occupy a broader
market in the future. In order to meet the market demand for the
lithium ion battery performance, the lithium ion battery with
higher performance will be researched in the future.
Conventionally, an anode of the lithium ion battery generally uses
copper oxide powders as an anode electrode material. The copper
oxide powders are coated and adhered on an current collector by
using a binder, the operation steps are numerous, and the
production process is cumbersome. Since the binder itself is not
electrically conductive and cannot contribute to the capacity, the
electron conduction is hindered and the specific capacity
decreases. Therefore, the lithium ion battery has a poor cycle
performance.
BRIEF DESCRIPTION OF THE DRAWINGS
Implementations of the present technology will now be described, by
way of embodiments, with reference to the attached figures.
FIG. 1 is a scanning electron micrograph of a nanoporous copper
substrate.
FIG. 2 is a flowchart of one embodiment of a method for making a
nanoporous copper supported copper oxide nanosheet array
composite.
FIG. 3 is a scanning electron micrograph of a copper hydroxide
formed by oxidation of the nanoporous copper substrate.
FIG. 4 is a Raman spectroscopy of a copper oxide.
FIG. 5 is a scanning electron micrograph of a copper oxide
nanosheet array oxidized a composite material is about 6 hours in a
0.016 M concentration of an ammonia solution concentration.
FIG. 6 is a scanning electron micrograph of a copper oxide
nanosheet array oxidized the composite material is about 12 hours
in a 0.033 M concentration of the ammonia solution
concentration.
FIG. 7 is a scanning electron micrograph of a copper oxide
nanosheet array oxidized the composite material is about 6 hours in
a 0.016 M concentration of the ammonia solution concentration.
FIG. 8 is a scanning electron micrograph of a copper oxide
nanosheet array oxidized the composite material is about 12 hours
in a 0.033 M concentration of the ammonia solution
concentration.
FIG. 9 is a cycle test diagram of an anode of the lithium ion
battery.
DETAILED DESCRIPTION
The disclosure is illustrated by way of example and not by way of
limitation in the figures of the accompanying drawings in which
like references indicate similar elements. It should be noted that
references to "an" or "one" embodiment in this disclosure are not
necessarily to the same embodiment, and such references mean "at
least one".
It will be appreciated that for simplicity and clarity of
illustration, where appropriate, reference numerals have been
repeated among the different figures to indicate corresponding or
analogous elements. In addition, numerous specific details are set
forth in order to provide a thorough understanding of the
embodiments described herein. However, it will be understood by
those of ordinary skill in the art that the embodiments described
herein can be practiced without these specific details. In other
instances, methods, procedures, and components have not been
described in detail so as not to obscure the related relevant
feature being described. Also, the description is not to be
considered as limiting the scope of the embodiments described
herein. The drawings are not necessarily to scale, and the
proportions of certain parts may be exaggerated to illustrate
details and features of the present disclosure better.
Several definitions that apply throughout this disclosure will now
be presented.
The term "comprise" or "comprising" when utilized, means "include
or including, but not necessarily limited to"; it specifically
indicates open-ended inclusion or membership in the so-described
combination, group, series, and the like.
An anode of lithium battery is provided. The anode comprises an
anode current collector and a copper oxide nanosheet array. In one
embodiment, the anode consists of the anode current collector and
the copper oxide nanosheet array. The anode current collector is a
nanoporous copper substrate. The copper oxide nanosheet array is
disposed on one surface of the nanoporous copper substrate. The
nanoporous copper substrate is chemically bonded to the copper
oxide nanosheet array. The copper oxide nanosheet array comprises a
plurality of copper oxide nanosheets. The plurality of copper oxide
nanosheets are perpendicular to the nanoporous copper substrate and
staggered to form an array structure.
The nanoporous copper substrate is a sheet structure. Referring to
FIG. 1, the nanoporous copper substrate comprises a plurality of
metal ligaments. The plurality of metal ligaments are staggered to
form a plurality of pores. The plurality of pores may be regularly
distributed or may be irregularly distributed. Diameters of the
plurality of pores range from about 20 nm to about 200 nm. A
thickness of the nanoporous copper substrate ranges from about 0.01
mm to about 1 mm. In one embodiment, the thickness of the
nanoporous copper substrate ranges from about 10 .mu.m to about 100
.mu.m, and the diameter of each of the pores ranges from about 20
nm to about 200 nm.
In one embodiment, the nanoporous copper substrate comprises a
reinforcement. The reinforcement is embedded in the porous of the
nanoporous copper substrate to improve a mechanical strength of the
nanoporous copper substrate. The material of the reinforcement can
be, but not limited to, a carbon nanotube structure or a graphene.
The carbon nanotube structure comprises at least one carbon
nanotubes. When the carbon nanotube structure comprises a plurality
of carbon nanotubes, the plurality of carbon nanotubes can be
randomly arranged, or the plurality of carbon nanotubes form a film
structure. The film structure comprises a drawn carbon nanotube
film, a pressed carbon nanotube film, or a flocculated carbon
nanotube film.
The plurality of carbon nanotubes in the drawn carbon nanotube film
are connected to each other end to end by van der Waals force and
arranged along a same direction. The plurality of carbon nanotubes
in the pressed carbon nanotube film are disordered and arranged in
the same direction or in different directions. The plurality of
carbon nanotubes in the flocculated carbon nanotube film are
attracted to each other by Van der Waals force and entangled to
form a network structure comprising micropores.
A height of a copper oxide nanosheet ranges from about 200 nm to
about 1.5 .mu.m. A thickness of the copper oxide nanosheet ranges
from about 20 nm to about 80 nm. The height of the copper oxide
nanosheet array refers to the length of the copper oxide nanosheet
perpendicular to the nanoporous copper substrate.
The anode of the lithium ion battery consists of the anode current
collector and the copper oxide nanosheet array, and the anode
current collector is chemically bonded to the copper oxide
nanosheet array. The copper oxide nanosheet array can use as an
anode material layer. That is, the anode current collector is
chemically bonded to the anode layer. The anode does not comprise a
binder, and the nanoporous copper substrate uses as the anode
current collector. Therefore, an internal resistance of the lithium
ion battery is reduced, an electron conduction is promoted, and a
conductivity of the lithium ion battery is improved. Moreover, an
electron conduction path can be effectively shortened. The above
factors are beneficial to an improvement of an cycle performance of
the lithium ion battery.
A flowchart is presented in accordance with an embodiment as
illustrated. The embodiment of a method 1 for making an anode of
lithium battery is provided, as there are a variety of ways to
carry out the method. The method 1 described below can be carried
out using the configurations illustrated in FIG. 2. Each block
represents one or more processes, methods, or subroutines carried
out in the method 1. Additionally, the illustrated order of blocks
is by example only, and the order of the blocks can be changed.
Method 1 can begin at block 101. Depending on the embodiment,
additional steps can be added, others removed, and the ordering of
the steps can be changed.
At block 101, the anode current collector is placed in an alkaline
solution comprising an ammonium ion, and the nanoporous copper
substrate floats on a surface of the alkaline solution comprising
the ammonium ion. The anode current collector is a nanoporous
copper substrate.
At block 102, the anode current collector reacts with the alkaline
solution comprising the ammonium ion to form a composite
material.
At block 103, the composite material is dried to form a nanoporous
copper supported copper oxide nanosheet array composite.
At block 101, the nanoporous copper substrate can be obtained by a
conventional method, such as a dealloying method. The nanoporous
copper substrate can be formed by dealloying an alloy substrate.
The alloy substrate is a copper alloy substrate, such as, a
copper-zinc alloy or a copper-aluminum alloy. The dealloying method
can be a method of free etching or electrochemical dealloying. A
thickness of the nanoporous copper substrate is related to a
thickness of the alloy substrate. The nanoporous copper substrate
is a sheet structure. The thickness of the nanoporous copper
substrate ranges from about 0.01 mm to about 1 mm. The nanoporous
copper substrate has a plurality of pores. A diameter of each of
the pores ranges from about 20 nm to about 200 nm. In one
embodiment, the thickness of the nanoporous copper substrate is
about 0.05 mm, and the diameter of each pore ranges from about 20
nm to about 200 nm.
The nanoporous copper substrate can be tailored to a size and shape
as required. The nanoporous copper substrate is gently placed on
the surface of the alkaline solution comprising the ammonium ion to
avoid damaging the nanoporous copper substrate and affecting a
morphology of a subsequently formed copper oxide nanosheet array.
Since the nanoporous copper substrate has a small density and a
high specific surface area, the nanoporous copper substrate can
freely float on the surface of an alkaline solution comprising the
ammonium ion. The alkaline solution comprising the ammonium ion is
an ammonia solution or a sodium hydroxide solution. A concentration
of the alkaline solution comprising the ammonium ion ranges from
about 0.016 mol/L to about 1 mol/L. In one embodiment, the
concentration of the alkaline solution comprising the ammonium ion
ranges from about 0.016 mol/L to about 0.033 mol/L. Further, a step
of removing impurities from the nanoporous copper substrate can be
comprised before block 101, so that a finally formed nanoporous
copper supported copper oxide nanosheet array composite has a good
morphology. In one embodiment, the nanoporous copper substrate can
be performed by a cleaning and drying treatment. Firstly, the
nanoporous copper substrate can be washed with hydrochloric acid to
remove the oxide layer on the surface of the nanoporous copper
substrate. Secondly, the nanoporous copper substrate is cleaned and
degreased by pure water or alcohol. A cleaned nanoporous copper
substrate is placed in a vacuum drying oven and dried for 2 hours
to 6 hours at a temperature in a range from about 140.degree. to
about 200.degree.. In one embodiment, the cleaned nanoporous copper
substrate is placed in the vacuum drying oven and dried at a
temperature of 80.degree. for 2 hours.
In one embodiment, the nanoporous copper substrate comprises a
reinforcement. The reinforcement is embedded in the porous of the
nanoporous copper substrate to improve a mechanical strength of the
nanoporous copper substrate. The material of the reinforcement can
be, but not limited to, a carbon nanotube structure or a graphene.
The carbon nanotube structure comprises at least one carbon
nanotubes. When the carbon nanotube structure comprises a plurality
of carbon nanotubes, the plurality of carbon nanotubes can be
randomly arranged, or the plurality of carbon nanotubes forms a
film structure. The film structure comprises a drawn carbon
nanotube film, a pressed carbon nanotube film, or a flocculated
carbon nanotube film.
The plurality of carbon nanotubes in the drawn carbon nanotube film
are connected end to end by van der Waals force and arranged along
a same direction. The plurality of carbon nanotubes in the pressed
carbon nanotube film are disordered and arranged in the same
direction or in different directions. The plurality of carbon
nanotubes in the flocculated carbon nanotube film are attracted to
each other by Van der Waals force and entangled to form a network
structure with micropores.
The method of forming the nanoporous copper supported copper oxide
nanosheet array composite does not affect a structure of the
reinforcement. When the nanoporous copper substrate comprises the
reinforcement, the nanoporous copper supported copper oxide
nanosheet array composite eventually formed also has the
reinforcement, and the structure of the reinforcement is
unchanged.
Referring to FIG. 3, at block 102, the nanoporous copper reacts
with the alkaline solution comprising the ammonium ion to form the
composite material, and the nanoporous copper is oxidized to form a
copper hydroxide array. That is, a nanoporous copper supported
copper hydroxide array composite is formed. Specifically, under an
action of oxygen, water molecules, ammonium ions, and hydroxides, a
surface of the nanoporous copper substrate in contact with the
alkaline solution comprising the ammonium ion is rapidly oxidized,
and a surface of the nanoporous copper substrate exposed to air is
not oxidized. The oxidation process occurs on one side of the
nanoporous copper substrate. An oxidation time of the nanoporous
copper substrate ranges from about 1 hour to about 72 hours. In one
embodiment, the oxidation time of nanoporous copper substrate
ranges from about 1 hour to about 12 hours. The oxidation time of
the nanoporous copper substrate can be shortened to 1 hour. In
another embodiment, the oxidation time of the nanoporous copper
substrate is 12 hours.
A rapid formation of the copper hydroxide array by oxidizing the
nanoporous copper substrate mainly depends on a coordination of the
ammonium ion, an activity of atoms at the metal ligament of the
nanoporous copper substrate, and a rapid oxygen transmission at the
surface of the alkaline solution. A principle of rapid oxidation
reaction of the nanoporous copper substrate is as follows: the
metal ligament of the nanoporous copper substrate has a small size,
and copper atoms at the metal ligament are chemically highly
active, so that the copper atoms are dissolved. The dissolved
copper atoms are located in a contact surface between the
nanoporous copper substrate and the alkaline solution comprising
the ammonium ion, and the contact surface has a high oxygen
concentration, thereby facilitating oxygen transmission. Therefore,
the dissolved copper atoms are oxidized by oxygen in the alkaline
solution to form divalent copper ions. Under an action of a strong
ligand (NH.sub.3), the divalent copper ions tend to form a
four-coordination ligand [Cu(H.sub.2O).sub.2(NH.sub.3)].sup.2+ with
a planar quadrilateral configuration. A formed copper ligand
continuously aggregates and grows at the metal ligament location, a
Cu(OH).sub.2 crystal with good thermodynamic stability is formed. A
nucleation and growth of Cu(OH).sub.2 crystal is supported by the
metal ligament, and the Cu(OH).sub.2 crystal growth mode is an
unidirectional growth. The Cu(OH).sub.2 crystal grows along a
gravity direction by a gravity pull, and a one-dimensional acicular
nano copper hydroxide array is formed.
At block 103, the composite material is dried and dehydrated in the
vacuum drying oven. The copper hydroxide array in the composite
material is converted into a copper oxide array to form the
nanoporous copper supported copper oxide nanosheet array composite.
The Raman spectrum of FIG. 4 indicates that the copper oxide array
is formed after drying and dehydrating the composite material, that
is, the copper hydroxide in the composite material is converted
into the copper oxide. The copper hydroxide undergoes a dehydration
reaction during a drying process, during which a significant atomic
diffusion occurs. Adjacent acicular copper hydroxide undergoes
polymerization under a surface energy action, and finally forms a
two-dimensional copper oxide nanosheet array. The height of the
copper oxide nanosheet ranges from about 200 nm to about 1.5 .mu.m,
and the thickness of the copper oxide nanosheet ranges from about
20 nm to about 80 nm.
A drying temperature and a drying time period of the composite
material are set in stages in order to form the copper oxide
nanosheet array having better crystallinity. In one embodiment,
firstly, the composite material is dried at a lower temperature to
remove part of water under mild conditions. Then, the temperature
is increased to achieve a polymerization growth of the copper oxide
to form the copper oxide nanosheet array with better crystallinity.
In one embodiment, the composite material is finally dried and
dehydrated at the temperature about 150.degree. C. or more. In
another embodiment, the composite material is finally dried and
dehydrated at the temperature about 180.degree. C.
FIGS. 5-8 show a scanning electron micrographs of the copper oxide
nanosheet under different oxidation conditions. In the FIG. 5, a
concentration of the ammonia solution concentration is about 0.016
mol/L, and an oxidation time of the composite material is about 6
hours. In the FIG. 6, the concentration of the ammonia solution is
about 0.016 mol/L, and the oxidation time of the composite material
is about 12 hours. In the FIG. 7, the concentration of the ammonia
solution is about 0.033 mol/L, and the oxidation time of the
composite material is about 6 hours. In the FIG. 8, the
concentration of the ammonia solution is about 0.033 mol/L, and the
oxidation time of the composite material is about 12 hours. As
shown in the FIGS. 5-8, when the oxidation time of the composite
material is the same, the larger the ammonia solution concentration
is, and the larger the size of the copper oxide nanosheet is. When
the ammonia solution concentration is the same, the longer the
oxidation time is, and the larger the size of the copper oxide
nanosheet is.
In order to form the copper oxide nanosheet array having a good
morphology, the composite material can be cleaned and dried to
remove impurities before drying the composite material at block
103. In one embodiment, the composite material is placed in pure
water or alcohol to clean the composite material, and then vacuum
dried.
The morphology of the copper oxide nanosheet array is related to a
concentration and type of the alkaline solution, the oxidation
time, a drying temperature time. Therefore, the concentration and
type of the alkaline solution, the oxidation time, the drying
temperature and the drying time can be adjusted to achieve a
required morphology of the copper oxide nanosheet array.
A lithium battery is provided in one embodiment. A lithium ion
battery comprises a cathode electrode, an anode electrode, a
separator, and an electrolyte solution. The cathode electrode and
the anode electrode are spaced from each other by the separator.
The cathode electrode comprises a cathode current collector and a
cathode material layer, and the cathode material layer is disposed
on a surface of the cathode current collector. The anode comprises
an anode current collector and a copper oxide nanosheet array. In
one embodiment, the anode consists of the anode current collector
and the copper oxide nanosheet array. The anode current collector
is a nanoporous copper substrate. The copper oxide nanosheet array
is disposed on one surface of the nanoporous copper substrate. The
nanoporous copper substrate is chemically bonded to the copper
oxide nanosheet array. The copper oxide nanosheet array comprises a
plurality of copper oxide nanosheets. The plurality of copper oxide
nanosheets are perpendicular to the nanoporous copper substrate and
staggered to form an array structure. The copper oxide nanosheet
array is used as an anode material layer. The anode material layer
and the cathode material layer are spaced from each other by the
separator.
The copper oxide nanosheet array is used as an anode material
layer, and the nanoporous copper substrate is chemically bonded to
the copper oxide nanosheet array. That is, the anode current
collector is chemically bonded to the anode layer. The anode does
not comprise a binder, and the nanoporous copper substrate uses as
the anode current collector. Therefore, an internal resistance of
the lithium ion battery is reduced, an electron conduction is
promoted, and a conductivity of the lithium ion battery is
improved. Moreover, an electron conduction path can be effectively
shortened. The above factors are beneficial to an improvement of a
cycle performance of the lithium ion battery.
The cathode material layer comprises a cathode active material.
Further, the cathode material layer can comprise a conductive agent
and a binder. The cathode electrode active material can be selected
from a layer type lithium transition metal oxide having a
structure, a spinel type lithium transition metal oxide, and an
olivine type lithium transition metal oxide, for example, olivine
type lithium iron phosphate, layer type lithium cobaltate, layer
type lithium manganate, spinel type lithium manganate, lithium
nickel manganese oxide and lithium nickel cobalt manganese oxide of
combination of them.
The binder in the cathode material layer can be selected from
polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE),
fluorine rubber, EPDM rubber, and styrene-butadiene rubber (SBR) of
combination of them.
The conductive agent in the cathode material layer can be selected
from graphene, carbon nanotubes, carbon fibers, conductive carbon
black, porous carbon, cracked carbon, acetylene black, activated
carbon, conductive graphite, and amorphous carbon of combination of
them.
The separator can be selected from a polyolefin porous film, a
modified polypropylene felt, a polyethylene felt, a glass fiber
felt, or a composite film. The composite film is formed by welding
or bonding an ultrafine glass fiber paper vinyl on felt or a nylon
felt and a wettable polyolefin microporous film.
The electrolyte solution comprises a lithium salt and a nonaqueous
solvent. The lithium salt can be one or more of lithium chloride
(LiCl), lithium hexafluorophosphate (LiPF.sub.6), lithium
tetrafluoroborate (LiBF.sub.4), lithium methanesulfonate
(LiCH.sub.3SO.sub.3), lithium trifluoromethanesulfonate
(LiCF.sub.3SO.sub.3), lithium hexafluoroarsenate (LiAsF.sub.6),
lithium hexafluoroantimonate (LiSbF.sub.6), lithium perchlorate
(LiClO.sub.4), Li[BF.sub.2(C.sub.2O.sub.4)],
Li[PF.sub.2(C.sub.2O.sub.4).sub.2], Li[N(CF.sub.3SO.sub.2).sub.2],
Li[C(CF.sub.3SO.sub.2).sub.3] and lithium bis(oxalate) borate
(LiBOB).
The nonaqueous solvent can selected from a cyclic carbonate, a
chain carbonate, a cyclic ether, a chain ether, a nitrile, and an
amide of combination of them, such as, ethylene carbonate (EC),
diethyl carbonate (DEC), propylene carbonate (PC), dimethyl
carbonate (DMC), ethyl methyl carbonate (EMC), butylene carbonate,
.gamma.-butyrolactone, .gamma.-valerolactone, dipropyl carbonate,
N-methylpyrrolidone (NMP), N-methylformamide, N-methylacetamide,
dimethylformamide, diethylformamide, diethyl ether, acetonitrile,
propionitrile, anisole, succinonitrile, adiponitrile,
glutaronitrile, dimethyl sulfoxide, dimethyl sulfite, vinylene
carbonate, ethyl methyl carbonate, dimethyl carbonate, diethyl
carbonate, fluoroethylene carbonate, anhydride, sulfolane,
methoxymethyl sulfone, tetrahydrofuran, 2-methyltetrahydrofuran,
propylene oxide, methyl acetate, ethyl acetate, propyl acetate,
methyl butyrate, ethyl propionate, ethyl propionate, methyl
propionate, dimethylformamide, 1,3-dioxolane, 1,2-diethoxyethane,
1,2-dimethoxyethane, 1,2-dibutoxy of combination of them.
Embodiment 1
In Embodiment 1, a nanoporous copper substrate having a size of 1
cm by 1 cm is provided. Firstly, the nanoporous copper substrate is
cleaned with hydrochloric acid to remove an oxide layer on surfaces
of the nanoporous copper substrate. Secondly, the nanoporous copper
substrate is degreased by pure water or alcohol. Finally, the
nanoporous copper substrate is dried in a vacuum drying oven at a
temperature of 80.degree. C. for 2 hours. Then, the nanoporous
copper substrate is oxidized as follows: the nanoporous copper
substrate is gently placed on a surface of a 0.033 mol/L ammonia
solution in a natural floating state at a room temperature for 12
hours, and the nanoporous copper is oxidized to form a composite
material (copper hydroxide array). The composite material is taken
out from the ammonia solution, washed in pure water and alcohol
respectively, and vacuum dried. Then, the dried composite material
is placed in the vacuum drying oven. Firstly, the vacuum drying
oven is set at a temperature 60.degree. C. for 2 hours; then the
vacuum drying oven is set at a temperature 120.degree. C. for 2
hours; finally the vacuum drying oven is set at a temperature
180.degree. C. for 2 hours, and naturally cooled to room
temperature to obtain the nanoporous copper supported copper oxide
nanosheet array composite. The copper oxide nanosheet array is
formed on one surface of the nanoporous copper substrate. An
average length of the copper oxide nanosheet under this condition
is about 1.2 .mu.m, and an average thickness of the copper oxide
nanosheets is about 40 nm.
An anode, a cathode, a separator and an electrolyte solution are
assembled into a button battery. The nanoporous copper copper oxide
nanosheet array composite is directly used as the anode of the
lithium ion battery. The cathode is a pure metal lithium plate, the
separator is a polymer material polyolefin porous film, and the
electrolyte solution is made of ethylene carbonate (EC) and
dimethyl carbonate (DMC). The volume ratio of ethylene carbonate
(EC) and dimethyl carbonate (DMC) is 1:1.
The assembled button battery undergoes a charge and discharge cycle
performance test at 0.1 mA cm.sup.-2 constant current. A test
voltage is greater than 0 V and less than or equal to 3 V. As shown
in FIG. 9, when cycle times of the button battery is 100 times, a
coulombic efficiency of the anode remains above 95%. It can be seen
that the lithium ion battery of the Example 11 has a good cycle
performance.
The method for making an anode of a lithium battery has the
following characteristics. First, a plurality of nanoporous copper
substrates prepared by different methods can be used to form the
copper oxide nanosheet array by an oxidation treatment. The
nanoporous copper substrate is easy to obtain. Second, the method
is convenient and efficient and without complicated and expensive
equipment. The method can be carried out at room temperature. The
nanoporous copper is rapidly oxidized to form the copper oxide
nanosheet array, and the morphology of the copper oxide nanosheet
is conveniently adjustable. Third, the copper oxide nanosheet array
is formed on one surface of the nanoporous copper. The nanoporous
copper supported copper oxide nanosheet array not only has the
performance of the copper oxide nanosheet array, but also retains
structural characteristics and properties of the nanoporous copper.
Therefore, the nanoporous copper supported copper oxide nanosheet
array realizes the structural and functional integration of the two
materials after compounding, and further fully synergizes the two
materials.
The method for making the anode and the lithium battery have the
following characteristics. First, the copper oxide nanosheet array
can be used as an active lithium storage layer. The nanoporous
copper as an anode current collector not only has excellent
electrical conductivity, but also can alleviate a volume change of
a copper oxide during charging and discharging. Therefore, a cycle
performance of the lithium ion battery can be improved. Further,
the copper oxide nanosheet array comprises a plurality of the
copper oxide nanosheets, and has a high specific surface area. The
high specific surface area can increase a contact area between the
electrolyte and the copper oxide, and effectively improve the
conductivity of copper oxide. The high specific surface area can
also shorten an electron conduction distance and increase the
electron conduction speed to improve the cycle performance of the
lithium ion battery. Second, the copper oxide nanosheet array is
chemically bonded to the nanoporous copper substrate. There is a
strong binding force between the copper oxide nanosheet array and
the nanoporous copper substrate. Therefore, the copper oxide
nanosheet array is not easily peeled off from the nanoporous copper
substrate. Third, there is no binder in the anode, the anode
consists of the anode current collector and the copper oxide
nanosheet array, and the nanoporous copper substrate uses as the
anode current collector. Therefore, an internal resistance of the
lithium ion battery is reduced, an electron conduction is promoted,
and a conductivity of the lithium ion battery is improved.
Moreover, an electron conduction path can be effectively shortened.
The above factors are beneficial to an improvement of a cycle
performance of the lithium ion battery. Fourth, when the nanoporous
copper substrate comprises the reinforcement, a mechanical strength
of the nanoporous copper substrate can be improved.
Even though numerous characteristics and advantages of certain
inventive embodiments have been set out in the foregoing
description, together with details of the structures and functions
of the embodiments, the disclosure is illustrative only. Changes
may be made in detail, especially in matters of arrangement of
parts, within the principles of the present disclosure to the full
extent indicated by the broad general meaning of the terms in which
the appended claims are expressed.
Depending on the embodiment, certain of the steps of methods
described may be removed, others may be added, and the sequence of
steps may be altered. It is also to be understood that the
description and the claims drawn to a method may comprise some
indication in reference to certain steps. However, the indication
used is only to be viewed for identification purposes and not as a
suggestion as to an order for the steps.
The embodiments shown and described above are only examples. Even
though numerous characteristics and advantages of the present
technology have been set forth in the foregoing description,
together with details of the structure and function of the present
disclosure, the disclosure is illustrative only, and changes may be
made in the detail, especially in matters of shape, size and
arrangement of the parts within the principles of the present
disclosure up to, and including the full extent established by the
broad general meaning of the terms used in the claims. It will
therefore be appreciated that the embodiments described above may
be modified within the scope of the claims.
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